Fix logic around showing search box

It was looking at the count of items at the root level (because it was
passing `parent_folder_id=None` as an argument).

This changes it to look at the total count of items for a service (which
was the intended behaviour).

app/models/service.py

@@ -369,7 +369,7 @@ class Service():
 
     @property
     def count_of_templates_and_folders(self):
-        return len(self.get_template_folders_and_templates('all', None))
+        return len(self.all_templates + self.all_template_folders)
 
     def move_to_folder(self, ids_to_move, move_to):
 

tests/app/main/views/test_templates.py

@@ -20,6 +20,7 @@ from tests import (
 from tests.app.main.views.test_template_folders import (
     CHILD_FOLDER_ID,
     PARENT_FOLDER_ID,
+    _folder,
 )
 from tests.conftest import (
     SERVICE_ONE_ID,
@@ -446,6 +447,33 @@ def test_should_show_live_search_if_list_of_templates_taller_than_screen(
     assert len(page.select(search['data-targets'])) == len(page.select('.message-name')) == 14
 
 
+def test_should_show_live_search_if_service_has_lots_of_folders(
+    client_request,
+    mock_get_template_folders,
+    mock_get_service_templates,  # returns 4 templates
+):
+
+    mock_get_template_folders.return_value = [
+        _folder('one', PARENT_FOLDER_ID),
+        _folder('two', None, parent=PARENT_FOLDER_ID),
+        _folder('three', None, parent=PARENT_FOLDER_ID),
+        _folder('four', None, parent=PARENT_FOLDER_ID),
+    ]
+
+    page = client_request.get(
+        'main.choose_template',
+        service_id=SERVICE_ONE_ID,
+    )
+
+    count_of_templates_and_folders = len(page.select('.message-name'))
+    count_of_folders = len(page.select('.template-list-folder'))
+    count_of_templates = count_of_templates_and_folders - count_of_folders
+
+    assert len(page.select('.live-search')) == 1
+    assert count_of_folders == 1
+    assert count_of_templates == 4
+
+
 def test_should_show_page_for_one_template(
     logged_in_client,
     mock_get_service_template,